Solid

A solid in chemistry and physics is a phase of matter [1] of matter [2] characterized by resistance to deformation and to changes of volume.

At the microscopic scale, a solid has these properties:

The atoms [3] or molecules [4] that comprise the solid are packed close together.

These constituent elements have fixed positions [5] in space relative to each other. This accounts for the solid's rigidity.

If sufficient force is applied, either of these properties can be violated, causing permanent deformation.

Because any solid has some thermal energy, its atoms vibrate. However, this movement is very small and very rapid, and cannot be observed under ordinary conditions.

The branch of physics [6] that deals with solids is called solid-state physics [7], and is a type of condensed matter physics [8]. Materials science [9] is primarily concerned with properties of solids such as strength and phase [10] transformations. It overlaps strongly with solid state physics. Solid-state chemistry [11] overlaps both of these fields, but is especially concerned with the synthesis of novel materials.

The lightest known solid is man-made and is called aerogel. The lightest aerogel produced has a density of 1.9 mg per cm3 or 1.9 kg/m3 (526.3 times lighter than water).